All-New Volvo V40 - World-First Pedestrian Airbag
Technology

SYDNEY – Feb 19, 2013: In China 25 percent of traffic fatalities
are pedestrians. In Europe the figure is 14 percent and in the USA 12
percent. Far larger numbers of pedestrians are injured.

The most serious head injuries involving pedestrians and cars are caused
by the hard structure under the bonnet panel, the windscreen’s lower
edge and the A-pillars.

These were some of the considerations when Volvo Car Group started
development of its Pedestrian Airbag technology. The system was a
world-first breakthrough when the All-New Volvo V40 was first launched at
the Geneva Motorshow in March 2012.

“We are proud to be able to offer a car with an airbag for
pedestrians,” says Thomas Broberg, Senior Technical Advisor Safety,
Volvo Car Group.

“The purpose of the airbag is to help protect pedestrians in
certain situations when they impact the bonnet and the area around the
windscreen wiper recess and A-pillar, where there may be a risk of serious
head injuries.”

Seven sensors embedded in the front of the car transmit signals to a
control unit. When the car comes into contact with an object, the signals
change. The control unit evaluates the signals and if it registers what it
interprets as a human leg the pedestrian airbag is deployed.

The bonnet hinges are each equipped with pyrotechnical release
mechanisms which, when the system is activated, pull out a pin and release
the rear of the bonnet panel. At the same time, the airbag is activated and
starts filling with gas. During the inflation sequence the airbag raises
the bonnet. It is lifted 10 centimetres and stays in the raised
position.

The added gap between the bonnet and the hard components in the engine
compartment gives space for the bonnet to deform, creating a dampening
effect when it is hit by a pedestrian.

“The Pedestrian Airbag has two functions. Firstly, it raises the
bonnet to create distance, and secondly it cushions the impact around the
hard parts of the area near the windscreen,” explains Thomas
Broberg.

In its inflated position, the airbag covers the entire windscreen wiper
recess, about one-third of the windscreen and the lower part of the
A-pillars. The entire sequence from activation of the system to full
inflation takes a few 100ths of a second.

The system is active at speeds between 20 and 50km/h – 75 percent
of all accidents involving pedestrians take place at up to 40km/h.

“We developed the technology using computer simulations and
human-like leg and head forms. The tests were carried out in a wide variety
of configurations,” relates Thomas Broberg.

The airbag itself consists of a sack and a gas hybrid generator. Upon
activation, the sack is filled with gas within a few milliseconds.

In 2010, the Volvo Car Group launched Pedestrian Detection with Full
Auto Brake. The system can avoid a collision with a pedestrian at speeds of
up to 35km/h if the driver does not respond in time. At higher speeds the
focus is on reducing the car’s speed as much as possible before the
collision